How do I set an older version of a program as the default?

Windows 10 is irritating me so hard right now. http://movieseriesworld.com/ It's literally allowed you to use user from settings to default. I have a version of Skype version http://www.movieseriesworld.com/forums/index.php to work, which is required automatically when some of these links are closed, but using the new version in Skype's Camera can not perform, but using the version of Skype in the camera can not be done, but use the new option of Skype

How do I get around this? I need the default program for you old version which is installed on the computer.